Performance verification of elastomer materials in corrosive gas and liquid conditions

摘要

Elastomer seals are essential for zonal isolation in vertical and deviated wells. They are often used either as O-rings (static seals) or as energized seals (packers). For elastomers to perform their functions effectively over an extended period, it is essential that the elastomer withstand the deleterious effects of pressure, prolonged loading effects, severe temperature, corrosive fluids, and acidic gases. As such it is imperative to understand the various elastomer degradation mechanisms and develop methods to reduce the degradation. The objectives of this study are: to investigate if elastomers are "fit for service" for well construction applications and to evaluate elastomer performances under downhole corrosive conditions. To achieve this goal, some dynamic wellbore conditions which close-to-real field conditions are were simulated in a controlled laboratory setup. The following properties were investigated: elastomer hardness, elastomer compression, and elastomer volumetric swelling. In the experimental setup, four frequently used elastomers in the oil and gas industry were studied: Nitrile butadiene rubber (NBR), Ethylene propylene diene monomer (EPDM), Fluoroelastomer (FKM) commonly known as Viton, and Polytetrafluoroethylene (PTFE). The results indicate that NBR exhibited the most significant deterioration. Viton showed the least amount of deterioration but has poor decompression resistance. The aging condition that proved to be the most damaging is CO2. Analysis of Variance (ANOVA) was also performed on the data from the samples as a statistical analysis indicator. Some other observations and conclusions are that the degree of chain growth and chain rupture depends on the temperature and the degree of chemical exposure.